The mechanisms of mucus secretion by the various glycoprotein-secreting cell types (mucous and serous cells in the submucosal glands and goblet cells in the airway epithelium) are being analysed in human bronchial mucosa maintained in vitro. Further analysis of the effects of vasoactive intestinal peptide and prostaglandins on glycoprotein secretion will be carried out, particularly their interaction with different secretagogues and antagonists. The effects of these agents will be compared in normal and bronchitic airways. In addition, we will carry out a preliminary study of the effects of various anti-inflammatory agents, particularly indomethacin and phenylbutazone. We will investigate the role of calcium ions in the secretion of glycoproteins, particularly their requirements in baseline and agonist-induced discharge. Further separation and characterization of mucus secreted by human bronchial explants in vitro will be carried out, particularly detailed analysis - carbohydrate and amino acid composition - of the major glycoprotein.